<!DOCTYPE html>
<html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title></title>
    <style media="screen">
      .box{
        width: 500px;
        border: 1px solid red;
        overflow: auto;
      }
      .left{
        height: 100px;
        width: 100px;
        background: blue;
        float: left;
      }
      .right{
        height: 100px;
        width: 100px;
        background: green;
        float: right;
      }
    </style>
  </head>
  <body>
    <div class="box">
      <div class="left"></div>
      <div class="right"></div>
      <!-- <div style="clear:both;"></div> -->
    </div>
  </body>
</html>
